Monitoring of drug levels

Abstract

The present invention provides a method of determining the concentration of a selected drug in the body of a subject comprising the steps of holding a liquid collecting means comprising an absorbent substantially inert member 1 in a position in close proximity to an eye 4 of the patient for collecting the fluid 7 therefrom; allowing the tear fluid collected to come into contact with reagent means 3 for reacting with said selected drug so as to produce, after a predetermined time interval, a physically detectable change dependent, at least semi-quantitatively, upon the concentration of said drug; and determining the physical change in said reactive portion after a predetermined interval of time.

What is claimed is: 
     
       1. A method of determining the concentration of a selected drug in the body of a subject comprising the steps of holding a liquid collecting means comprising an absorbent substantially inert member in a position in close proximity to an eye of the patient so as to contact surface tear fluid in the eye for collecting tear fluid therefrom; allowing the tear fluid collected to come into contact with reagent means for reacting with said selected drug so as to produce, after a predetermined time interval, a physically detectable change dependent, at least semi-quantitatively, upon the concentration of said drug; and determining the physical change in said reagent after a predetermined interval of time. 
     
     
       2. The method of claim 1 wherein the holding step comprises inserting and holding said member between the eyeball and eyelid of the subject, said member is in a form selected from the group consisting of a strip and a stick and comprises a fibrous material selected from the group consisting of natural and synthetic fibers. 
     
     
       3. The method of claim 2 wherein said collecting means has an absorbent member containing reagent connected thereto and said allowing step comprises diffusing said collected fluid into said reagent-containing means. 
     
     
       4. The method of claim 3 wherein said diffusing step includes placing the absorbent member in a reagent-containing vessel. 
     
     
       5. The method of claim 4 wherein said vessel comprises breachable wall means in said vessel forming plural compartments and at least first and second different reagents in different compartments, and said allowing step comprising bringing the tear fluid into contact with the first reagent, breaching the wall means and bringing the mixture of tear fluid and first reagent into contact with said second reagent. 
     
     
       6. The method of claim 1 wherein said physically detectable change is a visible color and said determining step comprises using a standard color reference for comparison with the color change by a process selected from the group consisting of spectrophotometry and direct visual comparison.